JPS6119900B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a refrigeration system (including a refrigeration system, hereinafter the same), and more particularly, the present invention relates to a refrigeration system (including a refrigeration system, hereinafter the same), and more particularly, the present invention relates to a refrigeration system (including a refrigeration system), and more particularly, the present invention relates to a refrigeration system (including a refrigeration system, hereinafter the same), and more particularly, the present invention relates to a refrigeration system (including a refrigeration system), and more particularly, the present invention relates to a refrigeration system (including a refrigeration system, hereinafter the same). The present invention relates to a device for controlling the timing of collecting ice.

BACKGROUND OF THE INVENTION It is common in the control of ice-making machines to take action on the ice that has formed as a function of the temperature in the refrigeration compartment in which the ice-making machine is located. The length of the time-controlled ice making cycle is varied according to the sensed temperature and is based on the assumption that the rate of ice formation is a linear function of the temperature within the refrigeration compartment.

However, such controls are sometimes imprecise, resulting in starting the harvest cycle before the ice is fully formed, or holding the ice-making cycle too long so that the ice is not completely formed before the harvest cycle begins. It was found that the ice formed in the process was continuously cooled, wasting energy.

A number of different systems for controlling ice making and harvesting cycles are disclosed in prior art patents. For example, Applicant's U.S. Pat. No. 3,648,478 discloses that means for timing the ice-making operation is activated only when the compressor is energized, and the length of the ice-making cycle is determined by the operating time of the compressor. A control for an ice making machine is disclosed. Therefore, in this patent, after a predetermined operating time of the compressor has elapsed, the control device automatically ends the ice-making operation and starts the ice-harvesting operation.

Other types of ice-making devices are disclosed in our other U.S. Pat. No. 3,714,794. In this patent, the timer motor operates continuously except when the temperature in the refrigeration compartment rises above a preselected temperature at which further operation of the ice maker is undesirable.

SUMMARY OF THE INVENTION The present invention provides an improved ice making machine in which the timing of ice making operations is determined by a differential temperature dependent function based on a determination of whether the temperature within the refrigeration compartment is above or below a predetermined temperature. Including control.

This control is based on a non-linear functional relationship between compartment temperature and freezing time, resulting in an improved system that virtually eliminates the formation of unfinished ice and the retention of energy-wasting ice-making cycles for too long. Provides precisely timed ice making operations. the result,
The efficiency of the ice-making operation is improved and the length of the ice-making cycle can be accurately controlled.

In broad terms, the invention provides means for sensing the temperature to which the water in the ice maker is exposed, and for calculating and storing a number corresponding to the cumulative sum of the individual temperature-dependent time increments determined periodically. and means for initiating an ice harvesting operation when the stored number reaches a predetermined number.

Specifically, the invention includes means for defining a sub-zero temperature compartment, an ice maker positioned within the compartment, and ice harvesting means for selectively harvesting ice from the ice maker. In refrigeration equipment,
sensing means for sensing the temperature in the compartment adjacent to the ice maker; and a first temperature-dependent function when the temperature sensed by the sensing means is higher than a predetermined temperature. a first calculating means for calculating a time-related number at preselected time intervals; and a second calculating means for calculating a time-related number at preselected time intervals; second calculation means for calculating at said preselected time intervals a time-related number based on a temperature-dependent function of said time-related numbers; and a sum of said time-related numbers at the end of each selected time interval. and means for operating the ice harvesting means when a preselected amount of the time-related number is accumulated. Including.

The invention further includes that different calculations are performed depending on whether air is forced to circulate through the refrigeration compartment by the air moving means.
In particular, the invention includes providing third and fourth additional calculation means for calculating appropriate time-related numbers when said air moving means is in operation.

In the exemplary embodiment, the controller periodically accumulates and stores temperature-dependent time increments defined by Δt/t. where Δt is a preselected time interval and t is the time required to freeze the water at the measured compartment temperature.

The time t is determined by the function T-b/m. where T is the temperature sensed at a particular time and b
is a constant and m is the slope at the sensed temperature of the curve defining the relationship between the compartment temperature and the time normally required to form ice at different compartment temperatures.

It has been found that the slope of the curve is substantially smaller for temperatures above the predetermined temperature than for temperatures below the predetermined temperature.

In the illustrated embodiment, these curves are based on a combination of the time required for perceptible cooling and latent cooling of the water within the ice maker.

The present invention thus encompasses an improved apparatus for controlling the operation of an ice maker that provides the highly desirable features described above and is very simple and economical to construct.

Other features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an exemplary embodiment of the invention, an ice maker 10, designated generally by the reference numeral 10, is mounted within a compartment 11 of a refrigeration system 12. The air in the compartment 11 is kept at a temperature below freezing by a suitable evaporator 13 in the rear wall 14.

In the illustrated embodiment, air moving means comprising an evaporator fan 15 moves air from the compartment 11 to the evaporator 13.
It is provided for forced circulation in a heat exchange relationship. The evaporator fan 15 is thermostatically controlled in a conventional manner to maintain the compartment at a temperature below freezing at all times.

As shown in FIG. 1, the refrigeration device 12 further includes:
It includes a compressor 16 for supplying refrigerant to a condenser 17, from which the refrigerant is supplied to the evaporator 13 via a capillary tube. A return path 18 is provided for returning the refrigerant from the evaporator 13 to the suction side of the compressor 16.

In the illustrated embodiment, the ice maker 10 includes a flexible tray 20 that includes a suitable mechanism for leaving the formed ice free within the cavity of the tray and allowing ice extraction. 21 and is periodically reversed and twisted. This is tray 20
is rotated about its longitudinal axis to reveal the lower compartment space 1 of the ice maker, as seen in FIG.
This is achieved by dropping free ice into the 1. Control of the ice forming and harvesting operations is carried out by a control device, generally indicated at 22, located adjacent to the twisting mechanism 21.

As shown in FIG. 2, control device 22 includes a timer motor 23 that drives twisting mechanism 21 through a series of gears 24. As shown in FIG. As shown, tray 20
is connected to the housing part 2 by means of a connector 26.
It is attached to 5. Water is periodically supplied into the tray via water valve 27. Free ice is received in a container 28 on the underside of the tray 20. A sensing arm 29 is connected to the controller 22 to sense the level of ice in the container 28 and automatically initiate an ice making cycle when the level of ice collected in the container reaches a preselected height. It is now scheduled to end in 2020.

As briefly mentioned above, the present invention includes an improved control system for ice making and harvesting cycles. The controller is a commercially available Texas Instrument TMS, as shown in Figure 2.
A microcomputer 30, such as a -2100 microcomputer. A clock crystal 31 is provided to establish timing signals for use in the computer, which is operated from a conventional regulated power supply 70.

In addition to the timing signal from crystal 31,
The microcomputer receives input from a temperature sensor 32 located adjacent to the ice maker. The microcomputer also receives an input indicating whether evaporator fan 15 is energized. This input is connected to a set of relay contacts 7, as shown in FIG.
2 is controlled by a relay (not shown) energized at the same time as the evaporator fan 15, a pull-up resistor 73 connected between the output of the regulated power supply and the input of the microcomputer. This can be provided by a set of connected relay contacts 72.

A first output from microcomputer 30 is applied to transistor 34 via resistor 33. This transistor 34 is a normally open switch 3 connected between the power supply lead L1 and the timer motor 23.
6 to selectively close relay coil 35.

A second output from the microcomputer is applied via a resistor 37 to a second transistor 38 for controlling a relay coil 39. The energization of coil 39 selectively closes a normally open switch 40 connected to water valve 27 in series with switch 36 .

In the illustrated embodiment, temperature sensor 32 is resistor 41
and a thermistor connected to form a voltage divider of the output of the regulated power supply 70. The output of this voltage divider provides a temperature dependent voltage input to the microcomputer 30 as shown. Each of relay coils 35 and 39 is connected to the output of a regulated power source.

Microcomputer 30 is programmed to provide improved control of the ice making cycle as a function of the temperature sensed by thermistor 32 to which tray 20 is exposed. In particular, the microcomputer determines according to a first temperature-dependent function when the temperature of the air sensed by the thermistor 32 is higher than a predetermined temperature; The sum of the individual temperature-dependent time increments determined by the second temperature-dependent function is accumulated in register 30a when the temperature of the air to be supplied is at or below said predetermined temperature, and a complete Ice extraction from the ice machine is controlled by initiating an ice extraction operation when a predetermined number of time increments have been accumulated that indicate ice formation.

As illustrated in FIG. 4, the actual time required to freeze the water in the ice maker tray 20 of a typical home refrigeration system is approximately It has been found that the linear functional relationship to refrigeration compartment temperature that has been utilized is substantially different. In particular, the functional relationship between the air temperature of the compartment to which the tray 20 is exposed and the time required to freeze the water within the tray clearly changes at a particular fixed temperature.
As illustrated, there are different functional relationships between time and temperature depending on whether the evaporator fan is on or off. Thus, as shown in FIG.
Figure 2 illustrates the time required to freeze water in tray 20 above and below T ₁ and when the evaporator fan is de-energized. Curve B illustrates the time required to freeze water at different temperatures above and below the second predetermined temperature _T2 when the evaporator fan is energized.

Curves A and B show approximately the time required to freeze the water in tray 20 as the temperature decreases until a temperature is reached where additional temperature decreases provide only a slight reduction in freezing time. It shows that it decreases in a linear manner. As illustrated, although the overall time-temperature relationship defined by curves A or B is non-linear, each of curves A or B is defined by two linear functions that intersect at points T ₁ or T _2, respectively. It can be approximated by

Thus, the predetermined temperature of curve A
The part 44 above T ₁ can be represented by the formula y=m ₁ x+b ₁ and the part 45 below the predetermined temperature T ₁ of curve A can be represented by the equation y=m ₂ x+b ₂ I can do it. Similarly, the portion 46 of curve B above the predetermined temperature T ₂ can be represented by the equation y=m ₃ x+b ₃ and the portion 47 of curve B below the predetermined temperature T ₂ can be represented by the equation It can be expressed by y=m ₄ x+b ₄ . The curve of FIG. 4 was determined empirically for an ice maker such as that shown in FIG. 1 with approximately 225 milliliters of water provided in the tray. These curves illustrate the total time required to provide both sensible and latent cooling. Here, perceptible cooling refers to the time required to cool water from an initial temperature of approximately 32°C (90°) to a temperature of 0°C (32°), and latent cooling refers to the time required to cool the water from an initial temperature of approximately 32°C (90°) to a temperature of 0°C (32°). The time required to freeze water at its temperature.

The different characteristics of the curve sections above and below a predetermined temperature are utilized in a novel manner in the controller 22 by the microcomputer 30 to provide the ice making device with improved accuracy of the ice making and harvesting cycles. Ru. Specifically, the program is entered at A and begins at block 48, as illustrated in the flowchart of FIG. At this block 48, the microcomputer's internal timer is set to zero and the transistor 38 switches the coil 39 for the appropriate amount of time to provide the desired amount of water to the ice maker tray 20.
energize. As mentioned above, the water is provided at ambient temperature, such as up to about 32°C.

The program proceeds to decision block 49 where it is determined whether the timer has reached the desired time Δt, thereby establishing the desired time period between temperature sampling and calculations made by the controller. A decision is made. This time period is tray 20
It should be considerably shorter than the total time required to freeze the water within, for example 1 minute. Thus, when the timer reaches Δt, block 49
A ``YES'' determination causes the program to proceed to decision block 50. At block 50, a temperature comparison is made to determine whether the sensed temperature T sensed by thermistor 32 is greater than a predetermined high temperature, such as about -2.8 DEG C. (27°). If the determination is ``YES'', the program repeats the temperature comparison until the point where the temperature of the compartment drops below the predetermined high temperature to ensure that the water in the tray freezes.

Upon determining that the sensed temperature is at or below a predetermined high temperature, the program advances to decision block 51 which determines whether evaporator fan 15 is energized.

If the fan 15 is energized, a ``YES'' determination in decision block 51 causes the program to proceed to decision block 52 where the sensed temperature is set to a predetermined temperature T2 _.
A determination is made whether the If it is determined that the sensed temperature is higher than the predetermined temperature _T2 , the program proceeds to block 53 where the calculation parameters of b and m are determined such that b=
b ₃ , m=m ₃ is set. The program proceeds to a calculation block 54 in which the computer calculates t=T-b ₃ /m ₃ . Here t represents the time in minutes it takes to freeze the water in tray 20 at a constant temperature T defined by curve B.

If the determination at decision block 52 is that the sensed temperature is lower than the predetermined temperature _T2 , the program proceeds to block 55;
In this block 55 the parameters b and m are set to b=b ₄ and m=m ₄ . From block 55 the program advances to block 56 where the computer calculates t=T-b ₄ /m ₄ .

If the determination at decision block 51 is that the evaporator fan is off, the program proceeds from block 51 to decision block 57 where the sensed temperature is equal to the predetermined temperature T ₁ of curve A. A higher or lower decision is made. If a determination is made that the sensed temperature is higher than the predetermined temperature _T1 , the program proceeds to block 58 where the parameters b and m are set such that b=
b ₁ and m=m ₁ . The program proceeds to block 59 where the computer calculates t=T-b ₁ /m ₁ .

If the determination at decision block 57 is that the sensed temperature is at or below the predetermined temperature _T1 , the program proceeds to block 60 where the parameters b and m are determined such that b=b2 _. and m= _m2 . The program proceeds to block 61 where the computer calculates t=T-b ₂ /m ₂ .

As mentioned above, the calculations in blocks 54, 56, 59 and 61 are such that, with the sensed temperature T and the set b and m parameters defined by curves A and B, the temperature remains at the measured value during the entire ice making cycle. It consists of determining the number corresponding to the total time t that would be required to freeze the water in the tray 20 if T remained constant. Since the sensed temperature T does not remain constant, the program proceeds from the appropriate block 54, 56, 59 or 61 to block 62 where Δt/t is calculated and the sum is accumulated. where Δt is the time period between calculations, which, as mentioned above, is one minute in the exemplary embodiment. Block 62 accumulates the sum of all periodic calculations of Δt/t during the ice making cycle. Assuming that the tray 20 is always exposed to a temperature of about -2.8 DEG C. or less, the accumulation or addition of the .DELTA.t/t calculation is performed once during each time period .DELTA.t.

The time period Δt is much shorter than the time t for freezing the water, thus each calculation Δt/t represents a time increment whose magnitude depends on the sensed temperature T. If Δt is equal to one minute, as is the case in the example embodiment, the ice-making cycle is completed when the sum of the calculated temperature-dependent time increments is equal to one.

Thus, the program proceeds from block 62 to decision block 63 where a determination is made whether the sum of the temperature dependent time increments is greater than or equal to one indicating that ice formation is complete. Until the point where the sum is greater than or equal to one, the program returns from the "NO" output of block 63 to input B leading to decision block 49, making the above-described decisions and The addition will be repeated.

If the sum of the sums determined in block 62 is greater than or equal to one, as determined in decision block 63, the "YES" output of block 63 controls block 64, which activates transistor 34 to energize coil 35. , closes contacts 36, thereby energizing ice maker drive motor 23 to begin the harvest cycle.

After the collection cycle, as illustrated in Figure 3,
The program returns to input A to begin the next controlled ice formation cycle.

Thus, the control technique illustrated in FIG. 3 provides an ice making cycle of variable length and correlated to sensed temperatures in which the ice maker is run according to different slopes of curves A and B illustrated in FIG. I will provide a. The present invention provides that the rate of ice formation in the tray increases in a substantially linear manner as the temperature decreases to a predetermined temperature, and that when this temperature further decreases below the predetermined temperature; By taking into account the fact that the rate of ice formation is only slightly increased, it provides improved accuracy in the control of the ice making cycle.

As noted above, curves A and B were determined empirically and, in the exemplary embodiment, are for a conventional plastic ice tray containing approximately 225 milliliters of water at an initial temperature of approximately 32°C. The transition points of these curves, and the curves themselves, will vary slightly depending on the particular air flow of the refrigeration system in which the ice maker is located.

Thus, in broad aspects, the present invention provides an ice maker controller that recognizes that ice formation rate is a non-linear function of temperature and that controls the ice making cycle according to a unique time-temperature curve for the ice maker. includes doing. The rate of ice formation was found to change rapidly in certain temperature regions where only a small increase in freezing rate occurred as the temperature was further reduced. Improved control of the timing of the ice-making cycle works to prevent improper sampling before the ice is fully formed and excessively long ice-forming cycles, thereby reducing the amount of ice that can be produced over a longer period of time. Maximize.

As will be apparent to those skilled in the art, the program illustrated in FIG. 3 is merely exemplary. Therefore, various changes to the program fall within the scope of the present invention.

The above description of specific embodiments is merely illustrative of the broader inventive concept encompassed by the present invention.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a portion of a refrigeration system having an ice maker equipped with a control device embodying the present invention; FIG. 2 is a partially cutaway schematic side view of the ice maker together with associated electrical circuitry; FIG. FIG. 4 is a flowchart illustrating a method for determining the timing of ice forming and harvesting operations; FIG. It is a characteristic diagram which illustrates a curve. 10: Ice maker, 11: Freezer section, 12: Refrigerator, 13: Evaporator, 15: Evaporator fan, 1
6: compressor, 17: condenser, 20: flexible tray, 22: control device, 23: timer motor, 27: water valve, 28: container, 29: sensing arm, 30: microcomputer, 32: temperature sensor, 36, 40: Always open switch, 35, 39:
Relay coil, 70: power supply, 72: relay contact.

Claims (1)

[Claims] 1. Means for defining a section with a temperature lower than the freezing point;
an air moving means for circulating air at a temperature below the freezing point into the compartment; an ice maker located within the compartment; and ice harvesting means for selectively harvesting ice from the ice maker. a refrigeration device comprising: sensing means for sensing a temperature within the compartment adjacent to the ice maker; and the temperature sensed by the sensing means is higher than a first predetermined temperature and the air movement a first for calculating at predetermined time intervals a number having a magnitude determined by a first temperature-dependent function when the means are not in operation;
a second temperature-dependent function when the temperature sensed by the sensing means is at or below the first predetermined temperature and the air moving means is not operating; a second calculating means for calculating a number having a magnitude determined by said predetermined time interval; a third for calculating at predetermined time intervals a number which is high and has a magnitude determined by a third temperature-dependent function when said air moving means is in operation;
and a fourth temperature-dependent function when the temperature sensed by the sensing means is at or below the second predetermined temperature and the air moving means is operating. fourth calculation means for calculating, at said predetermined time interval, a number having a magnitude determined by said temperature-dependent time interval, said predetermined time interval being a function of said calculated number; means for calculating an increment and accumulating a sum of said increments; and means for initiating operation of said ice harvesting means when a predetermined amount of said increment has been accumulated. Features ice maker control device. 2. said means for calculating and accumulating said increments, wherein Δt is said predetermined time interval and t is said calculated number determined by one of said temperature-dependent functions; 2. The ice maker control device according to claim 1, wherein the increment is determined as a function of Δt/t. 3 where T is the sensed temperature, b is a constant and m is the slope at said sensed temperature of the curve of the relationship between the compartment temperature and the time normally required to form ice at different compartment temperatures. Claim 1, wherein the calculated numbers are determined by calculating T-b/m, each of said calculated numbers representing the time required to form ice at a sensed temperature T. Ice maker control device as described. 4 where T is the sensed temperature, b is a constant and m is the slope at said sensed temperature of the curve of the relationship between the compartment temperature and the time normally required to form ice at different compartment temperatures. The calculated number is determined by calculating T-b/m, and the slope is substantially greater for temperatures above the predetermined temperature than for temperatures below the predetermined temperature. An ice maker control device according to claim 1, which is relatively small in scope. 5. The ice maker control device according to claim 1, wherein the ice collecting means comprises an ice collecting means that can be electrically energized.